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34:1 Metal Gearmotor 25Dx52L mm HP with 48 CPR Encoder
Details for item #2273
Exact gear ratio: (22×20×22×22×23) / (12×12×10×10×10) ≈ (34.014:1)
Gearmotor Options
This brushed DC gearmotor is available in high- and low-power versions in a number of gear ratios.
The motor and encoder portions are available by themselves (i.e. without the gearbox), and many
other gear ratios are also available without an encoder.
Gear
Ratio
No-LoadSpeed@
6V
1:1
4.4:1
9.7:1
20.4:1
34:1
47:1
75:1
99:1
172:1
227:1
378:1
499:1
9800 RPM
5600 RPM
2220 RPM
1280 RPM
1010 RPM
580 RPM
480 RPM
275 RPM
285 RPM
165 RPM
210 RPM
120 RPM
130 RPM
75 RPM
100 RPM
57 RPM
57 RPM
33 RPM
25 RPM
15 RPM
12 RPM
Stall Torque@ 6 V Stall Current@ 6 V
2 oz-in
1 oz-in
8 oz-in
5 oz-in
17 oz-in
11 oz-in
36 oz-in
24 oz-in
60 oz-in
40 oz-in
80 oz-in
50 oz-in
130 oz-in
85 oz-in
160 oz-in
110 oz-in
260 oz-in
170 oz-in
220 oz-in
250 oz-in
300 oz-in
With Encoder
6 A motor without gearbox
2.2 A motor without gearbox
6A
2.2 A
6 A 25Dx48L mm HP
2.2 A
25Dx48L mm
6A
2.2 A
6 A 25Dx52L mm HP
2.2 A
25Dx52L mm
6 A 25Dx52L mm HP
2.2 A
25Dx52L mm
6 A 25Dx54L mm HP
2.2 A
25Dx54L mm
6A
2.2 A
6A
2.2 A
25Dx56L mm
2.2 A
2.2 A
2.2 A
Without Encoder
25Dx48L mm HP
25Dx48L mm
25Dx48L mm HP
25Dx48L mm
25Dx50L mm HP
25Dx50L mm
25Dx52L mm HP
25Dx52L mm
25Dx52L mm HP
25Dx52L mm
25Dx54L mm HP
25Dx54L mm
25Dx54L mm HP
25Dx54L mm
25Dx56L mm HP
25Dx56L mm
25Dx56L mm
25Dx58L mm
25Dx58L mm
Note: At some of the higher gear ratios, these motors can generate enough torque to
damage themselves. Any torque greater than about 250 oz-in (18 kg-cm) is likely to
damage the gearbox, so we recommend that you avoid stalling the 172:1 HP, 227:1,
378:1, and 499:1 versions of these motors at 6 V.
These motors are intended for use at 6 V. In general, these kinds of motors can run at voltages
above and below this nominal voltage, so they should comfortably operate in the 3 – 9 V range,
though they can begin rotating at voltages as low as 1 V. Higher voltages could start negatively
affecting the life of the motor.
Gearmotor Dimensions
These gearmotors have output shafts with a diameter of 4 mm. The Pololu universal aluminum
mounting hub for 4mm shafts can be used to mount our larger Pololu wheels (60mm-, 70mm-,
80mm-, and 90mm-diameter) or custom wheels and mechanisms to the gearmotor’s output shaft
(see the left picture below). These are the same type of motors used in the Wild Thumper all-terrain
chassis, and the gearbox’s output shaft works directly with the 120mm-diameter Wild Thumper
wheels.
25D mm metal gear motor with 48 CPR
encoder and Pololu 60×8mm wheel.
The face plate has two mounting holes threaded for M3 screws. You can use our custom-designed
25D mm metal gearmotor bracket (shown in the picture below) to mount the gearmotor to your
project via these mounting holes and the screws that come with the bracket.
Pololu 25D mm gearmotor with bracket.
The diagram below shows the dimensions (in mm) of the 25D mm line of gearmotors. The value of L
is shown in the table below.
Gear
Ratio
Dimension diagram (in mm) for the 25D mm metal gearmotors.
L
(mm)
4.4:19.7:1
17
20.4:1
19
34.147:1
21
75:199:1
23
172:1227:1
25
378:1499:1
27
25D mm metal gearmotor with 48 CPR
encoder: close-up view of encoder.
Using the Encoder
A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear
protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per
revolution of the motor shaft when counting both edges of both channels. To compute the counts
per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six colorcoded, 11" (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main
product picture. This header works with standard 0.1″ male headers and our male jumper and
precrimped wires. If this header is not convenient for your application, you can pull the crimped wires
out of the header or cut the header off. The following table describes the wire functions:
Color
Function
Red
motor power (connects to one motor terminal)
Black
motor power (connects to the other motor
terminal)
Green encoder GND
Blue
encoder Vcc (3.5 – 20 V)
Yellow encoder A output
White
encoder B output
The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of
10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The
frequency of the transitions tells you the speed of the motor, and the order of the transitions tells you
the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder
outputs using a motor voltage of 6 V and a Hall sensor Vcc of 5 V:
Encoder A and B outputs for 25D mm HP metal gearmotor with 48 CPR encoder (motor running at 6 V).
By counting both the rising and falling edges of both the A and B outputs, it is possible to get 48
counts per revolution of the motor shaft. Using just a single edge of one channel results in 12 counts
per revolution of the motor shaft, so the frequency of the A output in the above oscilloscope capture
is 12 times the motor rotation frequency.
Selecting the Right Gearmotor
We offer a wide selection of metal gearmotors that offer different combinations of speed and torque.
Our metal gearmotor comparison table can help you find the motor that best meets your project’s
requirements.
Some of the Pololu metal gearmotors.
Documentation on producer website.